Grease composition



United States Patent 3,103,963 GREASE CDMPGSITIGN Bill L. Benge, Pouglrkeepsie, and Terence B. Jordan, Fishkill, N.Y., assignors to Texaco Inc, New York, N.Y., a corporation of Delaware N0 Drawing. Filed Dec. 8, 1961, fier. No. 158,111 (Jlaims. (Cl. 25233.6)

This invention relates to grease compositions and, more particularly, to lubricating grease compositions having improved stability and wear resistance to operations where high temperatures and high pressures are encountered.

It is known from US. 2,852,466 that grease compositions for high temperature operations can be prepared from oleaginous liquids such as, for example, hydrocarbon mineral oils and synthetic oils, containing as the thickener metal salts of N-acylamino organocarboxylic acids. However, none of the grease compositions specifically disclosed in this patent performs satisfactorily at the high temperatures required by Military Specification MIL- G-25760A.

It has now been found that specific sodium salts of N-(C )acylamino organocarboxylic acids in a particular oleaginous liquid exhibit unexpected advantages with respect to stability at high working temperatures and pressures. Accordingly, the grease compositions of the present invention comprise a base fluid containing a major portion of di-tridecyl sebacate and thickened with a sodium salt of N-acyl para aminobenzoic acid wherein the acyl group contains from 10 to 14 carbon atoms. In a particularly outstanding embodiment the acyl group contains 12 carbon atoms. The grease compositions of this invention contain, in addition, minor amounts of a refined mineral oil, an oxidation inhibitor and a rust inhibitor.

The grease compositions of this invention are designed to meet the severe requirements of Military Specification Test MILG25760A, covering a grease composition designed for high speed jet aircraft wheel and roller bearmgs.

Two of the more difficult requirements of this military specification are the CRC bearing protection test and the minimum of 400 hours service life at a 350 F. temperature in the high temperature performance test.

It has been found that grease compositions of the present invention comprise from 60 to 90% of a lubricating oil and 10 to 40% by weight, of a sodium salt of N(C acyl p-aminobenzoic acid as the thickening agent, said lubricating oil consisting of at least a major portion of ditridecyl sebacate. The composition usually contains 0 to 25% and preferably 5 to of a refined hydrocarbon mineral oil, 0.5 to about 5% of a grease corrosion inhibitor and 0.5 to about 5% of an arylamine type oxidation inhibitor, on a weight basis. The lubricating oil portion of the grease composition preferably contains the di-tridecyl sebacate and refined mineral oil in the ratio of about 3 to 7 parts of di-tridecyl sebacate per part of refined mineral oil. Such compositions exhibit superior stability at the high working temperatures encountered in present day high speed machinery in comparison with other grease compositions. The grease compositions of the invention can also contain minor amounts of lubricity agents, coloring materials, stringiness agents, tackiness agents, extreme pressure agents, etc.

A preferred composition is about 12 to percent sodium N-lauroyl p-amino benzoic acid, 10 to 16 percent refined mineral oil, 57 to 76 percent di-tridecyl sebacate, 1 percent N-cocoyl sarcosine corrosion inhibitor and 1 percent N,N-cliphenyl p-phenylene diamine as the oxidation inhibitor, on a weight basis.

Satisfactory arylamine oxidation inhibitors include diphenyl amine, phenyl alpha naphthylamine, p-phenylene diamine and N,N'-diphenyl-p-phenylene diamine. Satisfactory corrosion inhibitors include, for example, lead naphthenate and the N-acyl sarcosines containing from 8 to 20 carbon atoms in the acyl group, such as N-cocoyl sarcosine, N-lauroyl sarcosine and N-stearoyl sarcosine.

Following is a description by way of example of the grease compositions of the present invention.

EXAMPLE 1 A steam heated kettle equipped with a stirring mechanism was charged with.l2.4 parts of para (N-lauroyl) amino benzoic acid, 6.2 parts of a refined paratfin distillate oil, mineral oil A, having a viscosity at F. of 350 SUS, and 31 parts of water. The resulting admixture was stirred and heated to a temperature of to 190 F. and maintained at this temperature for 2 hours. Dur ing the heating operation there was added to the admixture 3.1 parts of sodium hydroxide (49.5 percent strength). Thereafter, the resulting mixture was heated to a temperature of 310 to 320 F. and maintained at this temperature for 3 hours while adding during the heating step over a period of time 12.4 parts of di-tridecyl sebacate. Thereafter, heating was discontinued and an additional 18.6 parts of di-tridecyl sebacate were added to the kettle. The resulting mixture was permitted to cool to a temperature of about 200 F. and the worked pene tration value of the resulting cooled admixture was adjusted to a value of 285-305 by the addition of 48 parts of an admixture of di-tridecyl sebacate and mineral oil A in the ratio of 5 parts of the ester per part of oil. The resulting mixture was stirred and there was added 1 part of N-cocoyl sarcosine and 1 part of N,N' diphenylparaphenylene diamine. The resulting batch was stirred until uniform, milled by 2 passes through a colloid mill and drawn at a temperature of F. The product was a brown colored grease having essentially the composition set forth in Table I hereinbelow.

EXAMPLES 2 TO 5 INCLUSIVE Following the procedure of Example 1 above, grease compositions were prepared in a similar manner. The compositions of the greases are tabulated in Table I below.

EXAMPLE 6 In a manner similar to Example 1, another grease was prepared using the sodium salt of N-stearoyl-p-aminobenzoic acid as the thickener and benzyl tridecyl azelate as the base fluid. Phenothiazine was used as the corrosion inhibitor. The composition of this grease is also shown in Table I below.

EXAMPLE 7 Following the procedure of Example 1 above, a grease was prepared using the sodium salt of N-stearoyl-p-aminobenzoic acid as the thickening agent, di-2-ethylhexyl sebacate as the base fluid and mineral oil B as the hydrocarbon oil. Mineral oil B is a refined paraflin distillate oil having a viscosity at 100 F. of 99.5 SUS. Lead naphthenate and phenyl alpha naphthylamine were used as the inhibitors. The composition of this grease is also shown in Table I below.

Table I Percent by Weight Ex. 1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Ex. 7

Sodium N-lauroyl paminobenzoic acid. 13.1 12. l 33. 4 19. 4 22. Excess NaOH 1 0.2 Mineral Oil A 14. 2 14. 3 16.1 13.0 10. 4 Dl'tridecyl sebacate. 70. 7 71. 6 48. 5 65. 0 65. 6 N-eocoyl sarcosine 1.0 1.0 1.0 1.0 Diphenyl p-phenyle diamine 1.0 1.0 1.0 1.0 1.0

Table II below shows some of the properties of the greases of Examples 1 to 7 inclusive as determined by standard grease testing procedures. In addition, the results are compared against the requirements of Government Specification MIL-G-25760A.

Table II as the base fluid pentaerythritol tetracaproate thickened with arylurea, Indanthrene Blue GCD and Baragel, respectively, failed to meet the minimum requirements for the bearing protection test and high temperature performance test of MIL-G-25760A. In contrast, as shown in Table II above, our grease compositions meet and exceeded the minimum test requirements of this specification We claim:

1. A grease composition comprising 60 to 90 percent lubricating oil and 10 to 40 percent by weight, of a sodium salt of N(C acyl p-aminobenzoic acid, said lubricating oil consisting of a least a major portion of ditridecyl sebacate.

2. A grease composition as claimed in claim 1 wherein the thickening agent is the sodium salt of N-lauroyl paminobenzoic acid.

3. A grease composition as claimed in claim 1 wherein the lubricating oil comprises 3 .to 7 parts of di-tridecyl sebacate per part of hydrocarbon mineral oil.

4. A grease composition as claimed in claim 1 comprising 89 to 40 percent of di-tridecyl sebacate, 0 to percent of a hydrocarbon mineral oil, 10 to 40 percent of the sodium salt of N-lauroyl p-aminobenzoic acid, 0.5 to 5 percent of a grease corrosion inhibitor and 0.5 to 5 percent of a grease oxidation inhibitor, on a weight basis.

5. A grease composition as claimed in claim 4 wherein the corrosion inhibitor is an N-acyl sarcosine containing from about 8 to 20 carbon atoms in the acyl group.

Tests on Product Limits Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Ex.7

ASTM Penetration 1 Unworked Worked 60 Strokes Dropping Point, F

Evaporation, percent 22 hrs., 350 F Oil Bleeding, percent hrs., 350 F Bomb Oxidation, 210 F., p.s.i. drop, 100 hrs Dynamic Water Resistance, percent Loss Steel on Steel Wear, 75 C. (167 F.) kg, 1,200 r.p.m.,

Scar diam, mm

Apparent Viscosity, -40 F., 20 see- Copper Strip Corrosion, 24 hrs., 212 (0 0 High Temp. Performance, hrs. at 350 F Storage Hardening:

Penetration after Gmonths 260-320 (8 295) m0. CRO Bearing Protection Test Pass Pass (3 mo (3 mo.) Pass Pass Pass Pass Fail Fail 1 Converted to ASTM, cone, worker used.

Inspection of the test results on the various grease compositions of Examples 1 to 7 inclusive in Table II above show that only the grease compositions of the present invention, namely, Examples 1 to 5 inclusive meet all of the requirements in the Government Specification MIL-G25760A. In particular it is seen that the grease compositions of Examples 6 and 7 failed to meet the requirements in the bearing corrosion test. The grease composition of Example 6 further failed to pass the dropping point and high temperature performance tests. Further, it is evident from the test data that the grease compositions of our invention are superior to the greases of Examples 6 and 7 since the greases of Examples 1 to 5 pass the bearing protection test and exhibit excellent performance at high temperatures.

In addition to the exceptional high temperature performance properties of the greases of this invention, these greases also shown the other desirable properties of a superior grease, including excellent Working stability, oxidation and corrsion resistance, water resistance and low oil bleeding.

The grease compositions of this invention are superior to competitive grease compositions designed for high temperature use. Three commercially available high temperature grease compositions comprising in each case 6. A grease composition as claimed in claim 5 wherein the grease corrosion inhibitor is N-cocoyl sarcosine.

7. A grease composition as claimed in claim 4 wherein the grease corrosion inhibitor is present in an amount of about 1 percent by Weight.

8. A grease composition as claimed in claim 4 wherein the grease oxidation inhibitor is N,N diphenyl-p-phenylene diamine.

9. A grease composition as claimed in claim 4 wherein the grease oxidation inhibitor is present in an amount of about 1 percent by weight.

10. A grease composition consisting essentially of from 12 to 25 percent sodium N-lauroyl p-aminobenzoic acid, 10 to 16 percent refined hydrocarbon mineral oil, about 57 to 76 percent di-tridecyl sebacate, about 1 percent N- cocoyl sarcosine as a corrosion inhibitor and about 1 percent N,N diphenyl p-phenylene diamine as an oxidation inhibitor, on a weight basis.

References Cited in the file of this patent UNITED STATES PATENTS 2,330,239 Prut-ton Sept. 28, 1943 2,852,466 Hotten Sept. 16, 1958 2,892,778 Carter et a1 June 30, 1959 2,999,813 Givens et a1. Sept. 12, 196 1 

1. A GREASE COMPOSITION COMPRISING 60 TO 90 PERCENT LUBRICATING OIL AND 10 TO 40 PERCENT BY WEIGHT, OF A SODIUM SALT OF N-(C10-14) ACYL P-AMINOBENZOIC ACID, SAID LUBRICATING OIL CONSISTING OF A LEAST A MAJOR PORTION OF DITRIDECYL SEBACATE. 